Arabinosyltransferase

Arabinosyltransferase refers to enzymes that catalyze the transfer of arabinose residues from activated donors to acceptors, forming glycosidic bonds. These enzymes participate in the biosynthesis and modification of arabinose-containing structures such as polysaccharides, glycoproteins, and glycolipids in a range of organisms, including bacteria and plants. They are a subset of glycosyltransferases that assemble arabinan-containing polymers and modify cell wall components.

Donor substrates vary by organism; nucleotide-activated arabinose (such as UDP-arabinose) is common, while lipid-linked donors such as decaprenylphosphoryl-D-arabinose are used by mycobacteria. Acceptors include arabinans, arabinogalactans, pectins, xylans, glycoproteins, and lipids. The resulting products contribute to cell wall architecture, matrix properties, and development.

Clinical and organismal examples: In Mycobacterium tuberculosis, EmbA, EmbB and EmbC catalyze arabinan formation in the cell wall arabinogalactan; ethambutol inhibits this pathway, making it a target for tuberculosis therapy. In plants, arabinosyltransferases modify cell wall polysaccharides and arabinose-containing side chains on proteins, affecting growth, cell wall integrity and defense responses.

Mechanistically, arabinosyltransferases are glycosyltransferases that can operate via retaining or inverting catalytic mechanisms. They range from soluble to membrane-associated enzymes and are distributed across several glycosyltransferase families. Understanding their function informs both antimicrobial strategies and plant bioengineering efforts.